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Biomedical subjects

W C Wu

Publications and source records attributed to W C Wu.

At least 19 recordsLinked to original sources
PubMed1992

Normal 24-hr ambulatory esophageal pH values. Influence of study center, pH electrode, age, and gender.

Although the most sensitive and specific test for diagnosing gastroesophageal reflux disease, normal standards for prolonged esophageal pH monitoring are based on small sample sizes with questions raised about the effects of pH electrode, older age, gender, and methods of data analysis on pH variables. Recently three groups have established normal data bases using similar methodology. Multiple regression and nonparametric analyses showed that the values for the six traditional pH parameters were comparable across study centers. Therefore, the groups were combined for a total study population of 110 healthy subjects (47 men, 63 women, mean age 38 years with a range of 20-84 years). Further nonparametric analyses revealed the following: (1) type of pH electrode (antimony vs glass) is not significantly related to parameters of physiologic acid reflux; (2) age is not independently related to pH parameters; (3) men tend to have more physiologic reflux than women; and (4) older men tend to experience longer episodes of reflux than younger men and women. There was a significant effect of gender and a significant interaction between age and gender on the number of episodes greater than 5 min (P = 0.008). Nearly significant differences were found for percentage of total acid exposure time (P = 0.03), total reflux episodes (P = 0.02), and the longest reflux episode (P = 0.02). We believe these normal esophageal pH values can be used confidently as standards in any laboratory, and consideration should be given to developing separate standards for men and women.

Adult↗
PubMed1992

Randomized, double-blind, placebo-controlled crossover trial of pirenzepine in patients with gastroesophageal reflux.

A muscarinic receptor subtype 1 (M1) antagonist, pirenzepine, recently has been shown to be relatively free of the usual anticholinergic side effects on esophageal smooth muscle and thus has been implicated for the treatment of gastroesophageal reflux disease (GERD). However, the effect of pirenzepine on GERD remains to be defined. Thirteen patients who demonstrated GERD in a baseline 24-hr ambulatory intraesophageal pH monitoring study were randomized in a double-blind crossover fashion to receive pirenzepine and placebo. An ambulatory 24-hr intraesophageal pH monitor was used to assess reduction in reflux (esophageal pH less than 4.0) with respect to position (upright vs supine), to total number of reflux episodes, and to episodes greater than 5 min. A significant effect for pirenzepine was seen for episodes greater than 5 min (t = 2.61, P = 0.023) and a trend towards significance was seen for total (upright and supine positions combined) percent time of reflux (t = 2.13, P = 0.055). Although not statistically significant, pirenzepine consistently showed greater reduction in all parameters of reflux tested. A greater reduction in percent time of reflux in supine vs upright positions (pirenzepine: 58.9% vs 21.4%; placebo: 43.6% vs 7.3%) may be clinically important in prevention of esophageal injury due to reflux in the recumbent position. Pirenzepine may provide a unique alternative for some GERD patients who may be refractory to other therapies of GERD.

Adult↗
PubMed1992

Prevalence of upper gastrointestinal disease in relation to age: radiologic and clinical implications.

Reports of 1126 endoscopies were reviewed to determine the age-related prevalence of upper gastrointestinal (UGI) diseases as a guide to radiologists performing UGI examinations. Results indicate that (1) there were positive findings in 78% of all endoscopic examinations, and thus most symptomatic patients can be expected to have at least one UGI abnormality; (2) many patients with UGI symptoms have two or more reportable disease processes; (3) the prevalence of serious or life-threatening disease, such as cancer or large ulcers, rises steadily with age; and (4) after age 60, approximately 60% of symptomatic patients have a serious UGI disease. Based on these findings, radiologists should not hesitate to make the diagnosis of multiple abnormalities and should expect to diagnose at least one abnormality in most symptomatic patients having an UGI study. Also, because of the high prevalence of serious lesions in the elderly, endoscopy should be considered for the initial examination of an elderly patient if poor physical status would render the radiologic examination difficult or unreliable.

Adolescent↗
PubMed1992

Coexistence of autonomic and somatic mechanisms in the pressor areas of medulla in cats.

The effects of electrical stimulation and microinjection of sodium glutamate (0.5 M) in the sympathetic pressor areas of the dorsal medulla (DM), ventrolateral medulla (VLM), and parvocellular nucleus (PVC) on the knee jerk, crossed extension, and evoked potential of the L5 ventral root produced by intermittent electrical stimulation were studied in 98 adult cats anesthetized with chloralose and urethane. During electrical and glutamate stimulation of these pressor areas, in addition to the rise of systemic arterial blood pressure marked inhibition of the spinal reflex was produced, indicating presence of neuronal perikarya responsible for these actions. Mild to moderate augmentation of spinal reflexes was also observed during brain stimulation but only in a few cases. The magnitude of the somatic effects among the pressor areas of the VLM, DM, and PVC subsequent to glutamate activation was about the same. Induced spinal reflex inhibition, independent from the baroreceptor and vagal influence, remained essentially unaltered after acute midcollicular decerebration. The inhibition was also observed in cats decerebellated 8-10 days in advance. The inhibition was not affected after bilateral electrolytic- or kainic-acid-induced lesions in the paramedian reticular nucleus (PRN). On the contrary, PRN-induced spinal reflex inhibition was attenuated after bilateral lesions in the DM or VLM. Data suggest that there coexists neuronal subpopulations in the VLM, DM, and PVC that can affect both the sympathetic pressor systems and spinal reflexes.

Animals↗
PubMed1992

Gastroesophageal reflux disease: correlation of esophageal pH testing and radiographic findings.

In an attempt to ascertain radiologic efficacy in patients with evidence of gastroesophageal reflux disease (GERD) at pH testing, radiographic findings were correlated with pH values obtained with an esophageal monitor worn for a 24-hour period in 112 patients. Fifteen (30%) of 50 patients with abnormal pH test results had esophagitis diagnosed radiographically, compared with six (10%) of 62 with normal pH test results (P < .05). The severity of abnormal pH monitoring results was classified but did not correlate significantly with the prevalence of esophagitis diagnosed radiographically. Hiatal hernia was also more common (80% vs 60%) in patients with abnormal pH test results (40 of 50 patients) than in those with normal results (37 of 62 patients) (P < .05). Pharyngeal, laryngeal, and pulmonary symptoms were common indications for evaluation, and 14 of 27 (52%) patients with hoarseness had an abnormal pH tracing. Only a minority of patients with evidence of GERD as defined by abnormal pH test results had reflux esophagitis diagnosed radiographically.

Adolescent↗
PubMed1991

Corneal wound healing after 193-nm excimer laser keratectomy.

As part of a human trial of phototherapeutic keratectomy, we performed anterior keratectomy using excimer laser 193-nm ablation on patients with superficial corneal opacities. We examined the ultrastructural changes in the corneas of four patients who underwent penetrating keratoplasty 6 to 15 months after excimer laser ablation. The four cases included macular dystrophy, recurrent keratoconus in a graft, and corneal scarring (two eyes). Light microscopy showed epithelial thickening, absence of Bowman's layer, and superficial stromal scarring in the area of ablation. Ultrastructural study showed that the epithelial basement membrane had focal discontinuities. At the margin of the ablation superficial collagen bundles terminated abruptly in a steplike configuration. The anterior stroma was scarred, with loss of lamellar structure and an increase in number of fibrocytes. The laser-induced scar was 10 to 15 microns thick in the two eyes without a stromal scar before laser ablation. The stroma underlying the scarred areas and that in the untreated area appeared normal. Linear collagen-like fibers were present in the posterior aspect of Descemet's membrane. Laser-induced scarring may be an important factor in limiting visual improvement in patients undergoing phototherapeutic keratectomy.

Adult↗
PubMed1991

Diffuse esophageal spasm. A rare motility disorder not characterized by high-amplitude contractions.

Diffuse esophageal spasm (DES) has frequently been described as a motility disorder characterized by simultaneous, high-amplitude contractions. We reviewed the results of esophageal manometry testing on a total of 1480 patients referred to our lab over 36 months. Lower esophageal sphincter (LES) pressure was determined by a mean of four station pull-through. Esophageal body motility was assessed following 10 wet swallows. In our lab a diagnosis of DES is made when greater than 10% but less than 100% of contractions are simultaneous. Manometric findings of DES were rare, with an overall prevalence of 4% (56/1480). Of the 56 patients with a manometric diagnosis of DES, high-amplitude (mean greater than or equal to 180 mm Hg) peristaltic contractions were found in only two (4%). No simultaneous contractions with amplitude greater than or equal to 180 mm Hg were seen. Pressures of simultaneous contractions were consistently lower than peristaltic contractions. A hypertensive LES pressure (greater than or equal to 45 mm Hg) was present in 5/56 DES patients (9%). Poor LES relaxation was found in 7/56 DES patients (13%). We conclude that DES is a rare manometric finding, regardless of the reason for referral, and that the occurrence of high-amplitude contractions in DES is equally rare.

Esophageal Spasm, Diffuse↗
PubMed1991

Radiographic evaluation of achalasia immediately after pneumatic dilatation with the Rigiflex dilator.

Radiographic evaluation of the lower esophagus was done immediately after pneumatic dilatation using the Rigiflex dilator in 34 patients (24 men, 10 women; mean age, 55 years) with achalasia. The dilator was positioned across the esophagogastic junction using fluoroscopy and the balloon was inflated for 1 min. The esophagus was intubated and injected sequentially with water-soluble and barium contrast materials. Radiographic analysis included changes in the appearance of the caliber and contour of the esophagogastric junction, rate of esophageal emptying, and presence of complications. In 23 patients with predilatation esophagrams, the mean esophagogastric junction caliber increased from 4.7-7.6 mm following dilatation. The postdilatation esophagrams in 33 patients showed a smooth contour in 22 (67%) and immediate esophageal emptying in 26 (79%). Esophageal perforation occurred in one (3%) patient and intramural hematoma in one (3%). Clinical follow-up (mean, 7 months) was available in 29 patients and 23 (79%) had symptomatic improvement. Five of the six patients who did not improve clinically all had previous Heller myotomy, pneumatic dilatation, or both.

Catheterization↗
PubMed1991

Exercise increases the circulating concentration of the N-terminus of the atrial natriuretic factor prohormone in normal individuals.

Recently two peptides consisting of amino acids (aa) 1 to 30 and 31 to 67 of the N-terminus of the 126 aa prohormone of atrial natriuretic factor (proANF), as well as atrial natriuretic factor (ANF, aa 99 to 126; C-terminus), were found to have vasodilatory and natriuretic properties. These peptides, as well as ANF, circulate in humans as part of the N-terminus of the prohormone. To determine the effect of graded exercise on the circulating concentrations of the N-terminus and C-terminus of the ANF prohormone in normal persons, 12 healthy individuals (mean age 45 +/- 2 years) were evaluated before, for 2 hours after, and during bicycle exercise at a work loads of 25, 50, 75, 100, 125, 150, and 175 W. Both the N- and C-terminus of the ANF prohormone were released simultaneously with graded exercise in direct proportion to the intensity of the work load, measured objectively via maximal oxygen consumption (VO2max), respiratory quotient, and heart rate. Both the N-terminus and C-terminus of the ANF prohormone had strong positive correlations (p less than 0.001) with blood pressure, heart rate, VO2max, and respiratory quotient. Following exercise, the C-terminus returned to preexercise levels within 30 minutes, while the N-terminus remained significantly elevated at 30 and 60 minutes postexercise, reflecting the longer half-life of the N-terminus in the circulation.

Adult↗
PubMed1991

Enteral feeding tubes: placement by using fluoroscopy and endoscopy.

Fluoroscopy and endoscopy are both effective for guiding placement of enteral feeding tubes, but the relative advantages and limitations of the two methods are less clear. Consequently, we studied 104 consecutive patients referred for primary fluoroscopic placement of a Frederick-Miller feeding catheter. Success rate, fluoroscopic and room times, and tube position were determined. Unsuccessful fluoroscopic placement was followed immediately by an endoscopic attempt. The success rate for fluoroscopic placement was 90% (94/104), with the tube placed into the jejunum in 53% and into the duodenum in 47%. The fluoroscopic and room times for successful fluoroscopic placements were 8.6 +/- 5.6 min (mean +/- SD) and 21.7 +/- 8.4 min, respectively. For the 10 unsuccessful placements, the fluoroscopic and room times were 16.2 +/- 5.4 min (mean +/- SD) and 45.6 +/- 18.4 min, respectively. Both time differences were significant statistically. Endoscopic placement was successful in all seven patients in whom it was attempted, with a mean time of 13.4 min. The tubes placed endoscopically were in the jejunum in 29% and in the duodenum in 71%. Our results show that fluoroscopic and endoscopic placement of enteral feeding tubes is highly effective. Fluoroscopic time in successful cases is usually less than 15 min. Endoscopic placement of feeding tubes is successful after fluoroscopic failure.

Adult↗
PubMed1991

Transfer from ophthalmology to another service is a marker of high risk medical events.

Of 3632 consecutive admissions to the Wilmer Ophthalmological Institute between July 1, 1987 and June 30, 1989, 27 patients required transfer to a medical or surgical service (0.74%). The major reasons for transfer included acute or decompensated cardiac disease (26%), poorly controlled diabetes mellitus (19%), acute renal failure (11%), coagulopathy, stroke, and hypertension (7% each). Only one transfer was a direct result of an anesthesia complication. The highest rates of transfers were associated with orbital (4.3%), enucleation/evisceration (3.1%), and glaucoma (2.3%) surgeries, while vitreoretinal surgery had the lowest rate of transfer (0.3%). Most of the transfers of patients with orbital disease were for management of related problems such as sinusitis or increased intracranial pressure.

Adult↗
PubMed1991

Use of a marshmallow bolus for evaluating lower esophageal mucosal rings.

Sixty-three patients (35 women, 28 men; mean age 55 yr) with lower esophageal mucosal ring shown radiographically were examined with a semi-solid bolus consisting of a portion of a standard marshmallow. The most common symptom was dysphagia, present in 46 (73%) patients. Impaction of the marshmallow bolus by the ring occurred in 40 (63%) of the 63 patients, and produced symptoms in 27 (68%) of these 40 patients. Nine (14%) rings were detected radiographically only with a solid bolus; eight of these patients had dysphagia and seven rings were 20 mm or less in caliber. Impaction related to ring caliber, and was found in all 17 (100%) rings that were 13 mm or less in diameter, in 17/24 (71%) 14- to 19-mm rings, and in 6/22 (27%) rings 20 mm or more in caliber. Endoscopy in 23 patients detected 16 (70%) rings, and also depended on ring caliber: less than or equal to 13 mm, 6/6 (100%); 14-19 mm, 5/9 (56%); greater than or equal to 20 mm, 5/8 (63%). Marshmallow impaction occurred in 17 (74%) of 23 patients who had endoscopy; three of the 23 patients had normal endoscopy. In conclusion, radiographic examination supplemented by the use of a marshmallow bolus best detects lower esophageal mucosal ring.

Constriction, Pathologic↗
PubMed1990

Inhibition of spinal reflexes by paramedian reticular nucleus.

The inhibitory actions of the paramedian reticular nucleus (PRN), and its neighbouring structures, i.e., midline raphe nuclei (MRN) and dorsal medullary depressor area (DMD) on the knee jerk (KnJ) and crossed extension movement (CEM) induced by central sciatic stimulation and on the L5 ventral root response (EVRR) evoked by central tibial stimulation, were studied in cats under urethane (400 mg/kg) and alpha-chloralose (40 mg/kg) anesthesia alone, IP or further paralyzed with atracurium besylate (0.5 mg/kg/30 min), IV. Electrical stimulation of the above areas with rectangular pulses (80 Hz, 1.0 msec, 100-200 microA) decreased systemic arterial blood pressure (SAP) in an average value of: 36 +/- 3 mmHg for PRN; 19 +/- 2 mmHg for MRN; and 23 +/- 3 mmHg for DMD. The KnJ and CEM were almost completely suppressed by simultaneous PRN stimulation. The EVRR, including mono- and polysynaptic spinal reflexes with transmission velocity from 10 to 60 m/sec or above, were also suppressed. MRN stimulation only inhibited the KnJ, CEM and polysynaptic spinal reflexes with transmission velocities between 25 and 60 m/sec, but facilitated spinal reflexes with conduction velocities below 10 m/sec. On the other hand, DMD stimulation resulted in small suppression of KnJ, CEM and inhibition of polysynaptic spinal reflexes with conduction velocities between 25 and 60 m/sec. Even though MRN and DMD partially inhibited polysynaptic spinal reflexes, the magnitude of such inhibition was much smaller than that produced by PRN (-20% and -22% vs. -48%). The above-mentioned PRN effects on SAP and EVRR persisted in chronic animals decerebellated 9-12 days before.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Radiologic evaluation of esophageal motility: results in 170 patients with chest pain.

The role of radiologic evaluation of esophageal motility in patients with chest pain has been studied rarely. Consequently, we compared the results of radiologic and manometric examinations of the esophagus in 170 patients (106 women, 64 men; mean age, 53 years) with chest pain. Manometry, used as the standard, was normal in 114 (67%) patients, and showed the following abnormal diagnoses in the remaining 56 (33%): nonspecific esophageal motility disorder in 27 (48%), nutcracker esophagus in 16 (29%), diffuse esophageal spasm in 11 (20%), and achalasia in two (4%). Radiologic specificity was 93% (106/114) and overall sensitivity only 36% (20/56). Sensitivity increased to 50% by excluding those with nutcracker esophagus, a purely manometric diagnosis. Of the 20 patients in whom nonspecific esophageal motility disorder and diffuse esophageal spasm were undetected on radiologic examination, minimal manometric criteria for diagnosis were available in 18. Our results show that radiologic recognition of normal esophageal peristalsis is excellent. However, the vast majority of patients with chest pain do not appear to have abnormal esophageal motility on radiologic evaluation.

Adult↗
PubMed1990

The prevalence of abnormal esophageal test results in patients with cardiovascular disease and unexplained chest pain.

The purpose of our study was to assess the prevalence of esophageal test abnormalities in patients with known cardiovascular disease and persistent chest pain. We performed a retrospective review of symptoms, manometry, and provocative test results performed on patients with undiagnosed chest pain. The 220 patients with angiographically determined cardiac disease and persistent chest pain were divided into three groups: coronary artery disease (125 patients), mitral valve prolapse (38 patients), and coronary bypass/angioplasty (57 patients). A comparison group consisted of 159 patients with noncardiac chest pain. All patients underwent esophageal manometry and placebo-controlled provocative testing (acid perfusion test and edrophonium chloride test). The prevalence of esophageal motility disorders in the noncardiac chest pain group (27%) was similar to that in the coronary artery disease (24%), mitral valve prolapse (37%), and coronary bypass/angioplasty (30%) groups. The frequency of nutcracker esophagus (11% to 16%) and diffuse esophageal spasm (2% to 7%) was remarkably constant. The prevalence of any positive provocative result in the noncardiac chest pain group (27%) was similar to that in the coronary artery disease (19%), mitral valve prolapse (32%), and coronary bypass/angioplasty (20%) groups. Furthermore, completely negative results of esophageal investigation occurred in 55%, 62%, 42%, and 59% of the respective patient groups.

Acids↗
PubMed1990

Prospective randomized comparison of Brown-McHardy and microvasive balloon dilators in treatment of achalasia.

We report the results of a randomized prospective study comparing a standard bougie rubber balloon dilator [Brown-McHardy (BMH)] and a newer polyethylene dilator passed over a guide wire [Microvasive Rigiflex (MVR)]. Twenty achalasia patients (15M, 5F, mean age 45.4 yr) considered candidates for either dilator were randomized. Symptom assessment, body weight, and upright radionuclide solid esophageal emptying study were measured before and 6 months after pneumatic dilatation. All dilatations were performed by one of three experienced gastroenterologists under fluoroscopic guidance. Overall success occurred with 10/10 BMH and 7/10 MVR. One patient not improved with MVR had myotomy; the other two were successfully treated by BMH. No complications occurred with either dilator.

Adult↗
PubMed1990

Ancillary tests in the diagnosis of gastroesophageal reflux disease.

This article reviews some of the diagnostic procedures for gastroesophageal reflux disease other than the procedures of choice, endoscopy and prolonged intraesophageal pH monitoring. The author discusses the roles of the acid perfusion (Bernstein) test, radiology, manometry, and radionuclide scintigraphy in the diagnosis and management of gastroesophageal reflux disease.

Chest Pain↗